Device for display of information with complete scanning beam arrest

ABSTRACT

A device for display of information has a receiver-amplifier unit connected to a source of an information signal, horizontal and vertical scanning generators, a converter of the signal into the displayed image, which is connected to the horizontal and vertical scanning generators, an output amplifier, a detector of image contours, connected to the receiver-amplifier unit, a threshold unit connected to the image contour detector, a control signal generator connected to the threshold unit and the output amplifier. Thus, complete scanning beam arrest is accomplished.

BACKGROUND OF THE INVENTION TECHNICAL FIELD

1. Field of the Invention

This invention relates to picture transmission techniques, e.g.television systems using, in particular, line-by-line or interlacedscanning, and is, more specifically, concerned with devices for datadisplay.

2. Description of the Related Art

Known in the art is a device for display of information (U.S. Pat. No.2,678,964), comprising a high-frequency amplifier, a frequencyconverter, an intermediate frequency amplifier, a video detector, avideo amplifier, a sound channel, line and frame generators, a picturetube featuring a deflection system, and some other additional unitsintended to improve the sharpness of the picture. In this prior artdevice, the sharpness of the picture is achieved by slowing down thespeed of the line scanning, when reproducing the image outlines, or, inother words, in response to any fast changes in the brightness of thepicture. To this end, the device additionally comprises severalseries-connected units, such as an image contour detector, an outputamplifier, and one more line deflecting coil (apart from the coil of thedeflection system) or line deflecting plates. In this device, the inputof the image contour detectors is connected to the output or input ofthe video amplifier. This image contour detector comprises one or twodifferentiating circuits and may include a signal level limiter.

The disadvantage of this data display device consists in that theenhancement in the sharpness of the picture is not substantial. This isdue to the non-rectangular shape of the signal produced by the imagecontour detector. Since the duration of this signal is equal to theduration of the edge of the video signal from which it is produced, thissignal has an intricate shape containing several alternating halfwaves.The scanning beam is therefore arrested for only a part of the durationof the video signal edge and not for the complete duration thereof.

Known in the art is a data display system (U.S. Pat. No. 4,080,628)comprising a high frequency amplifier, a frequency converter, anintermediate frequency amplifier, a video detector, a video amplifier, asound channel, line and frame generators, a picture tube with adeflection system, an image contour detector, an output amplifier, andone more line deflection coil (in addition to the coil in the deflectionsystem) or line deflection plates. In the image contour detector, theoutput signal is produced by differentiating the video signal, full wavelimitation of this video signal, summing the limited signal with theinitial video signal, and subsequent second differentiation of theobtained sum. This signal is supplied, via an output amplifier, tohorizontal deflecting plates or horizontal deflection coils.

This known system is deficient in that the scanning beam is arrested, todisplay the image edges, only for a period much shorter than theduration of a respective edge of the video signal. The enhancement ofthe sharpness of the picture is therefore not substantial.

SUMMARY OF THE INVENTION

The invention is to provide a data display system having a circuitmaking it possible to achieve a complete stop of the scanning beam forthe period during which the luminance of the displayed image, whichdepends on the video signal applied to the picture tube, changes inorder to substantially enhance the sharpness of the picture and,consequently, the reliability of the displayed image.

The invention consists in that a data display device comprising areceiver-amplifier unit having a line synchronization output, a framesynchronization output, at least one information output, and an inputconnected to an information signal source, and designed to receive,amplify, and isolate an information video signal, and to separate theline and frame sync signals, horizontal and vertical generatorsproducing a standard pattern and having their inputs connectedrespectively to line and frame sync outputs of the receiver-amplifierunit, a signal-to-image converter designed to produce the image on thepicture tube screen and having its first input connected to the outputof the horizontal scanning generator, its second input connected to theoutput of the vertical generator, and its third input electricallyconnected to an information output of the receiver-amplifier unit, anoutput amplifier having its output connected to a fourth input of thesignal-to-image converter, a displayed image contour detector designedto produce a signal to control the process of horizontal scanning fordisplaying the image contours and having its input connected to theinformation output of the receiver-amplifier unit, according to theinvention, comprises a threshold unit connected to the output of thedisplayed image contour detector and designed to achieve, during displayof image contours, a near zero or insignificant speed of the horizontalbeam scanning, a control signal generator producing sawtooth voltagewhen displaying image edges and having its first input connected to theoutput of the threshold unit, while the output thereof is connected tothe input of the output amplifier which is to convert the sawtoothvoltage into a sawtooth current producing a deflecting field of the samestrength as the field produced by the horizontal scanning generator butof the opposite polarity.

It is preferable that the data display device should comprise acorrector of geometrical distortions of the displayed image, which is toprevent spacial shifts of edges of the displayed image and has its firstinput connected to the output of the threshold unit, its second inputconnected to the line sync output of the receiver-amplifier unit, andits output connected to a second input of the control signal generator.

It is possible that the data display device should comprise a correctorof luminance distortions of the displayed image, which is designed toprevent distortions of the luminance levels of the edges of thedisplayed image and background and which is inserted into the electricalconnection between the information output of the receiver-amplifier unitand a third input of the signal-to-image converter, a second input ofthis luminance distortion corrector being connected to the output of thethreshold unit, while its third input is connected to the output of thedisplayed image geometrical distortion corrector.

It is also possible that the data display device should comprise twoadditional correctors of image luminance distortions, which are tocorrect the luminance levels of chrominance signals and which have theirfirst inputs connected respectively to the second and third informationoutputs of the receiver-amplifier unit, their second inputs connected tothe output of the threshold unit, and their third inputs connected tothe output of the image geometrical distortion corrector, while theoutputs thereof are connected to the fifth and sixth inputs of thesignal-to-image converter.

It is reasonable that the image luminance distortion corrector of thedata display device should comprise a difference amplifier designed tosubtract a signal generated in the threshold unit from the sourceinformation signal summed up with the signal fed from the output of theimage geometrical distortion corrector, one input of said differenceamplifier being connected to the output of the threshold unit, anotherinput thereof being connected to the output of the image geometricaldistortion corrector, while a third input thereof is connected to theinformation output of the receiver-amplifier unit, and the output of thedifference amplifier is connected to the input of the signal-to-imageconverter.

It is also reasonable that the image geometrical distortion correctorshould comprise first and second delay units, an analog storage unit, anOR circuit having its first input connected to the output of thethreshold unit, its second input connected to the line sync output ofthe receiver-amplifier unit, and its output connected to inputs of thefirst delay unit, of the second delay unit, and of the analog storageunit, a logarithmic amplifier, a differentiating unit, a sawtoothvoltage generator having its input connected to the output of the firstdelay unit, while the output thereof is connected to the logarithmicamplifier coupled to the differentiating unit having its outputconnected to the second input of the analog storage unit, ananalog-to-digital converter, a digital-to-analog converter, a digitalstorage unit having its first input connected to the second delay unit,its second input connected to the output of the analog-to-digitalconverter coupled to the output of the analog storage unit, while theoutput of the digital storage unit should be connected to thedigital-to-analog converter whose output is the output of the imagegeometrical distortion corrector, connected to the input of the controlsignal generator.

It is quite possible that the image geometrical distortion correctorshould comprise a peak detector, an electronic switch, an analog shiftregister, a first delay unit having its input connected to the output ofthe threshold unit, and its output connected to the peak detector, asecond delay unit whose input should be connected to the line syncoutput of the receiver-amplifier unit, while the output thereof isconnected to a control input of the electronic switch having one signaloutput connected to a common bus and the other signal output connectedto a second input of the peak detector having an output connected to asignal input of the analog shift register, an OR circuit having oneinput connected to the output of the threshold unit, another inputconnected to the line sync output of the receiver-amplifier unit, andthe output thereof is connected to the control input of the analog shiftregister, a reversible counter, a third delay unit having its inputconnected to the output of the OR circuit and its output connected tothe substracting input of the resersible counter whose summing input isconnected to the output of the OR circuit, and a multiplexer having itsN signal inputs connected to N outputs of the analog shift register andhaving M control inputs connected to outputs of the reversible counter,and M log N, while the output of the multiplexer is the output of theimage geometrical distortion corrector, connected to the input of thecontrol signal generator.

It is possible that the analog shift register should comprise 2N-1series-connected analog storage units, uneven storage units having theiroutputs connected to signal inputs of the multiplexer, and a delay unithaving its input connected to control inputs of uneven analog storageunits, while the output thereof is connected to control inputs of evenanalog storage units.

This invention makes it possible to achieve a much higher sharpness ofthe image displayed on the CRT screen, because it practically eliminatesthe effect of the limited resolution of pick-up tubes and the limitedbandwidth of the communication channel on the sharpness of the displayedimage by ensuring a complete arrest of the scanning beam when displayingthe edges of the image. It also becomes possible to obtain ahigh-quality picture even using low-cost portable TV reporting camerasand cheap video tape recorders. The sharpness of the picture remainsgood when cheap or sophisticated TV equipment is used and practicallydepends only on the quality of the TV receiver. Enhanced sharpness ofthe displayed picture achieved by the use of the present invention canalso contribute to lessen the eye fatigue caused by watching TVprograms.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described in greater detail with reference tospecific embodiments thereof and accompanying drawings, wherein:

FIG. 1 shows a block diagram of a data display device applicable tomonochrome pictures, according to the invention;

FIG. 2 shows a block diagram of a data display device applicable tocolor pictures, according to the invention;

FIG. 3 shows a block diagram of a displayed image contour detector,according to the invention;

FIG. 4 shows a block diagram of an image luminance distortion correctorequipped with an analog multiplier, according to the invention;

FIG. 5 shows a block diagram of an image luminance distortion correctorwithout the analog multiplier, according to the invention;

FIG. 6 shows a block diagram of an image geometrical distortioncorrector equipped with a digital storage unit, according to theinvention;

FIG. 7 shows a block diagram of an image geometrical distortioncorrector equipped with analog storage units, according to theinvention;

FIG. 8 shows a circuit diagram of a control signal generator equippedwith an analog inverter, according to the invention;

FIG. 9 shows a circuit diagram of a control signal generator featuringan analog difference amplifier, according to the invention;

FIGS. 10a, b, c, d, e, f, g, h show curves explanatory of the operationof the data display device of FIG. 1 for a case when pulse-separationaverage components are defined between the leading edges of the pulses,according to the invention;

FIGS. 11a, b, c, d, e, f, g, h show curves explanatory of the operationof the data display device of FIG. 1 for a case when pulse-separationaverage components are defined between the trailing edges of thesepulses, according to the invention;

FIGS. 12a, b, c, d show curves explanatory of the operation of the imagecontour detector, according to the invention;

FIGS. 13a, b, c, d, e, f show curves explanatory of the operation of theimage luminance distortion corrector of FIG. 4, according to theinvention;

FIGS. 14a, b, c, d show curves explanatory of the operation of the imageluminance distortion corrector of FIG. 5, according to the invention;

FIGS. 15a, b, c, d, e, f, g, h, i show curves explanatory of theoperation of the image geometrical distortion corrector of FIG. 6,according to the invention;

FIGS. 16a, b, c, d, e, f, g, h, i, j, p, r, s, u show curves explanatoryof the operation of the geometrical distortion corrector of FIG. 7,according to the invention;

FIGS. 17a, b, c show curves explanatory of the operation of controlsignal generators illustrated in FIGS. 8 and 9, according to theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An information display device comprises a receiver-amplifier unit 1(FIG. 1) having its input connected to an output of an informationsignal source 2. This information signal source 2 may be an antenna, atape recorder, a pick-up TV camera. The receiver-amplifier unit 1employs a known circuit (V. K. Zvorykin et al. Televidenie, 1956,Inostrannaya literatura Publ., Moscow, pp. 528-548) and has thefollowing outputs: a line sync output producing line sync pulses, aframe sync output producing frame sync pulses, and at least oneinformation output. When only black-and-white (or monochrome) picture isdisplayed, there is only one information output available and the videosignal is taken off therefrom. The receiver-amplifier unit 1 is designedto receive, amplify and separate an information video signal, and lineand frame synchronization signals.

The information display device also comprises a horizontal scanninggenerator 3 and a vertical scanning generator 4, both employing knowncircuits. The input of the horizontal scanning generator 3 is connectedto the line sync output of the receiver-amplifier unit 1. The input ofthe vertical scanning generator 4 is connected to the frame sync outputof the receiver-amplifier unit 1. The horizontal and vertical scanninggenerators 3 and 4 are designed to produce a standard pattern.

The information display device also comprises a converter 5 of a signalinto a displayed image, which may, for example, be made as a picturetube equipped with a deflection system and appropriate power supplycircuits and controls. The signal-to-image converter 5 is designed toproduce a picture on the screen of the tube. First and second inputs ofthe signal-to-image converter 5 are connected to outputs of thehorizintal and vertical scanning generators 3 and 4 respectively.

The information display device also comprises a corrector 6 of luminancedistortions of the displayed image, which has its first input connectedto an information output of the receiver-amplifier unit 1, an imagecontour detector 7 having its input connected to an information outputof the receiver-amplifier unit 1 and which is designed to producecontrol signals for the horizontal scanning process of image contourdisplay.

The information display device also comprises a threshold unit 8, e.g. acomparator or a monovibrator (W. Tietze et al. Poluprovodnikovayaskhemotekhnika, 1983, Mir Publ., Moscow, pp. 286-292), which has itsinput connected to the output of the image contour detector 7 and isdesigned to achieve, during display of image edges, the speed ofhorizontal scanning, which is constant and close to zero. Theinformation display device comprises a corrector 9 of geometricaldistortions of the displayed image and a control signal generator 10.The output of the threshold unit 8 is connected to first inputs of theimage geometrical distortion corrector 9 and of the control signalgenerator 10 and to the second input of the image luminance distortioncorrector 6. The third input of the image luminance distortion corrector6 is connected to an output of the image geometrical distortioncorrector 9, which is also connected to the second input of the controlsignal generator 10. The second input of the geometrical distortioncorrector 9 is connected to the line sync output of thereceiver-amplifier unit 1.

The device for display of information, according to the invention, alsocomprises an output amplifier 11 designed to convert sawtooth voltageinto sawtooth current producing a deflecting field of the same strengthas the field produced by the horizontal scanning generator 3, but havingthe opposite polarity. An output of the control signal generator 10 isconnected to the output amplifier 11. This output amplifier 11 may bebuilt around a known circuit (SU, A, 879818). The output of the outputamplifier 11 is connected to a fourth input of the signal-to-imageconverter 5. The third input of the signal-to-image converter 5 isconnected to the output of the luminance distortion corrector 6.

To display color information, the functional block diagram of theinformation display device shown in FIG. 2 is analogous to thefunctional diagram of the device in FIG. 1 with the followingexceptions. The receiver-amplifier unit 1 (FIG. 2) has three informationoutputs feeding signals for red, green, and blue colors. The informationdisplay device also comprises two additional correctors 6 of luminancedistortions of the displayed image, which are to correct the brightnesslevels of chrominance signals and have their first inputs connected,respectively, to the second and third information outputs of thereceiver-amplifier unit 1, their second inputs connected to the outputof the threshold unit 8, and their third inputs connected to the outputof the image geometrical distortion corrector 9, while the outputsthereof are connected to fifth and sixth inputs of the signal-to-imageconverter 5.

The image contour detector 7 comprises the following series-connectedcomponents: a delay unit 12 (FIG. 3), e.g. a delay line rated for 50-100ns, a difference amplifier 13, and a full-wave rectifier 14 (W. Tietzeet al. Poluprovodnikovaya skhemotekhnika, 1983, Mir Publ., Moscow, pp.137-140, 470-472).

The corrector 6 of luminance distortions of the displayed image isdesigned to prevent distortions of the luminance levels of the imageedges and its background and comprises a difference amplifier 15 (FIG.4) coupled in series to a one-quadrant analog multiplier 16 (W. Tietzeet al. Ppoluprovodnikovaya Skhemotekhnika, 1983, Mir Publ., Moscow, pp.158-165). An inverting input 17 of the difference amplifier 15 isconnected to the output of the threshold unit 8, while a non-invertinginput 18 is connected to the output of the image geometrical distortioncorrector 9.

The difference amplifier 15 is built around an operational amplifier 19,for example, see W. Tietze et al. above, pp. 67-72. The inverting inputof the operational amplifier 19 is connected to a resistor 20, while thenon-inverting input thereof is connected to a resistor 21. A resistor 22is inserted between the output of the operational amplifier 19 and itsinverting input. The movable contact of a potentiometer 24 is connectedto the non-inverting input of the operational amplifier 19 via aresistor 23, while one of the stationary contacts thereof is connectedto a source 25 of constant bias voltage and the other stationary contactis connected to a common bus 26. Another input of the one-quadrantanalog multiplier 16 is connected to an information output of thereceiver-amplifier unit 1, while the output thereof is connected to theinput of the signal-to-image converter 5.

The luminance distortion corrector 6 may be a difference amplifier 27(FIG. 5) designed to subtract the signal produced in the threshold unit8 from the source information signal summed up with the signal fed fromthe output of the geometrical distortion corrector 9. One input of thedifference amplifier 27 is connected to an output of the threshold unit8, another input is connected to the output of the geometricaldistortions corrector 9, and a third input is connected to aninformation output of the receiver-amplifier unit 1. The output of thedifference amplifier 27 is connected to the input of the signal-to-imageconverter 5. The difference amplifier 27 may be built around anoperational amplifier 28 whose inverting input is connected to theoutput of the threshold unit 8 via a resistor 29, while thenon-inverting input thereof is connected to the output of thegeometrical distortion corrector 9 via a resistor 30 and to aninformation output of the receiver-amplifier unit 1 via a resistor 31.The output of the operational amplifier 28 is connected to the input ofthe signal-to-image converter 5. A resistor 32 is inserted between theoutput of the operational amplifier 28 and its inverting input, while aresistor 33 is inserted between the non-inverting input of theoperatonal amplifier 28 and the common bus 26.

The corrector 9 of geometrical distortions of the displayed image isdesigned to prevent any shifts in space of the edges of the displayedimage and comprises an OR circuit 34 (FIG. 6) having its first inputconnected to the threshold unit 8, its second input connected to theline sync output of the receiver-amplifier unit 1. The output of the ORcircuit 34 is connected to inputs of a delay unit 35 (e.g. a delay lineor a univibrator triggered by the trailing edge of the input pulse), anda delay unit 36 (e.g. a univibrator). The output of the threshold unit 8and the sync output of the unit 1 are connected to control inputs of ananalog storage device 37 (e.g. a sample-and-hold circuit), see W. Tietzeet al. Poloprovednikovaya Teknika, 1983, Mir Publ., Moscow, pp. 284-285.

The output of the delay unit 35 is connected to a sawtooth voltagegenerator 38 whose output is connected to a logarithmic amplifier 39 (W.Tietze et al., pp. 148-150). The output of the logarithmic amplifier 39is connected to a differentiating unit 40 which may be, for example, adifference amplifier 41 having a delay line 42 rated for 50-100 nsinserted between its inputs. The output of the differentiating unit 40is connected to a signal input of the analog storage device 37 havingits output connected via an analog-to-digital converter 43 to a digitalstorage unit 44, e.g. a single-chip storage (W. Tietze et al., pp.454-464, 392-397). Another input of the digital storage 44 is connectedto the output of the delay unit 36 rated for a period approximatelyequal to the horizontal scan period. The output of the main storage 44is connected to an input of a digital-to-analog converter 45 (W. Tietzeet al., pp. 444-454) having its output, as the output of the geometricaldistortion corrector 9, connected to the input of the control signalgenerator 10.

The geometrical distortion corrector 9 may be built around anothercircuit. This embodiment of the corrector 9 has identical delay units 46and 47 (e.g. univibrators or delay lines) joined to the input thereof.The output of the delay unit 46 is connected to a first input of a peakdetector 48 built around a known circuit. The output of the delay unit47 is connected to a control input of an electronic switch 49 having itsfirst signal output connected to the common bus 26 and its second signaloutput connected to a second input of the peak detector 48. The outputof the peak detector 48 is connected to a signal input of an analogshift register 50. This analog shift register may be realized as aplurality of 2N-1 series-connected analog storage units 51 (e.g.sample-and-hold circuits), where N is the number of signal outputs ofthe analog shift register 50. Signal outputs of the analog shiftregister 50 are outputs of the uneven analog storage units 51 whosecontrol inputs are connected to the output of an OR circuit 52 havingits first input connected to the output of the threshold unit 8, itssecond input connected to the line sync output of the receiver-amplifierunit 1. Control inputs of the even analog storage units 51 of the analogshift register 50 are connected to an output of its own delay unit 53(e.g. a univibrator or a delay line) having its input connected to theoutput of the OR circuit 52. The output of the OR circuit 52 isconnected directly to a summing input of a reversible counter 54 and,via a delay unit 55 (e.g. a univibrator or a delay line), to thesubstracting input thereof. Outputs of all stages of the reversiblecounter 54 are connected to control inputs of a multiplexer 56 (W.Tietze et al., pp. 326-328). Besides, the N signal inputs of themultiplexer 56 are series-connected to N outputs of the analog shiftregister 50. The output of the multiplexer 56 is the output of thegeometrical distortion corrector 9, which is connected to the input ofthe control signal generator 10.

The control signal generator 10 produces sawtooth voltage when the imageedges are displayed and comprises an analog inverter 57 coupled inseries with an inverting integrator 58. An input 59 of the analoginverter 57, which is an input of the control signal generator 10, isconnected to the output of the threshold unit 8. An input 60 of theinverting integrator 58, which is another input of the control signalgenerator 10, is connected to the output of the geometrical distortioncorrector 9.

The analog inverter 57 comprises an operational amplifier 61 having itsoutput connected, via a resistor 62, to the first input thereofconnected, via a resistor 63, to the input 59 of the analog inverter 57.The second input of the operational amplifier 61 is connected, via aresistor 64, to the common bus 26. The output of the operationalamplifier 61 is connected, via a resistor 65 of the inverting integrator58, to a first input of an operational amplifier 66 having its outputconnected, via a capacitor 67, to the first input thereof and, via aresistor 68, to the output of the geometrical distortion corrector 9. Asecond input of the operational amplifier 66 is connected, via aresistor 69, to the common bus 26. The output of the operationalamplifier 66 is connected to the output amplifier 11.

An alternative embodiment of the control signal generator 10 is made asa difference amplifier 70 coupled in series with an integrator 71. Anoninverting input 72 of the difference amplifier 70 is connected to theoutput of the geometrical distortion corrector 9, while an invertinginput 73 thereof is connected to the output of the threshold unit 8.

The difference amplifier 70 comprises an operational amplifier 74 havingits output connected, via a resistor 75, to its inverting input and, viaa resistor 76, to the output of the threshold unit 8. The noninvertinginput of the operational amplifier 74 is connected, vis a resistor 77,to the output of the geometrical distortion corrector 9 and, via aresistor 78, to the common bus 26. The output of the operationalamplifier 74 is connected, via a resistor 79, to the inverting input ofan operational amplifier 80. The operational amplifier 80 has itsnoninverting input connected, via a resistor 81, to the common bus 26,and its output connected, via a capacitor 82, to the inverting inputthereof and the output amplifier 11.

The device for display of information shown in FIG. 1 operates asfollows.

The source information is supplied from the information signal source 2to the receiver-amplifier unit 1 on a carrier or video frequency. It isconverted into horizontal synchronization pulses taken off from the linesync output, vertical synchronization pulses taken off from the framesync output, and video signals (curve 83 in FIGS. 10a and 11a) taken offfrom the information output. These pulses have the required magnitudeand polarity. Horizontal synchronization pulses are fed to thehorizontal scanning generator 3 (FIG. 1) and vertical synchronizationpulses are fed to the vertical scanning generator 4, thus providingstandard (interlaced) scanning of the picture on the screen of the CRTwhich is a part of the signal-to-image converter 5. The video signal(curve 83 in FIGS. 10a and 11a) is supplied from the information outputof the receiver-amplifier 1 (FIG. 1) to the image contour detector 7,where it is converted into an analog signal which corresponds to theabsolute value of the first derivative of the video signal (curve 84 inFIGS. 10b and 11b). This signal is unified in the threshold unit 8, inother words, the signal is transformed into uniform pulses having thesame magnitude, and polarity (curve 85 in FIGS. 10c and 11c). Thesepulses are fed to the control signal generator 10 (FIG. 1) where theyare converted into sawtooth voltage (curve 86 in FIGS. 10e and 11e).This sawtooth voltage is converted by the output amplifier 11 intocurrent producing a deflection field having the same strength as thefield produced by the horizontal scanning generator 3 (curve 87 in FIGS.10d and 11d) but the opposite polarity. These fields are algebraicallysummed up to produce a deflection field (curve 88 in FIGS. 10f and 11f)capable of arresting the scanning beam when displaying the imagecontours corresponding to respective pulse edges in the original videosignal (curve 83 in FIGS. 10a and 11a).

Horizontal portions of the resulting deflecting field (curve 88 in FIGS.10f and 11f) correspond to the zero scanning speed. Since the beam isarrested practically for the complete period while the video signal fedto the tube changes, the sharpness of the displayed image is increasedby a factor of more than two, that is almost to the maximum. Since thebeam scanning speed control channel in the herein disclosed devicecomprises the threshold unit 8, the dependence of the improvement in thesharpness of the picture on the signal swing is completely eliminated.On the other hand, to keep the brightness of the screen from growingduring the display of image contours due to the well known relationbetween the luminance and scanning speed, the video signal magnitudeshould be additionally changed to match the changes in the beam scanningspeed (curves 89 and 90 in FIGS. 10g, 11g, 10h and 11h). This isrealized in the corrector 6 of the luminance distortions of thedisplayed image, which is inserted between the information output of thereceiver-amplifier unit 1 and the third input of the signal-to-imageconverter 5.

In order to prevent geometrical distortions of the displayed image dueto modulation of the scanning speed, the beam should move faster todisplay the background as compared to the situation where the scanningspeed is not modulated. This accelerated beam speed should be exactlythe same as if the beam displays the image contours in the same placeswhen no modulation of the scanning speed is available. To this end, theaverage speed of the electronic beam between any two adjacent contoursshould be constant and equal to the average speed of the beam over thepattern. This can be achieved in two ways: when the beam moves faster inthe background portion of the picture and stops to display the imagecontour (curve 88 in FIG. 10f), that is when the average beam speedbetween the trailing edges of adjacent contours is constant, or, in thesecond way, when the beam stops at the contour and then moves faster atthe adjacent background portion (curve 88 in FIG. 11f), that is when theaverage scanning speed is kept constant between the forward edges of anytwo adjacent image contours. This program is realized in the corrector 9of geometrical distortions of the displayed image.

Introduction of the luminance distortion corrector 6 and the geometricaldistortion corrector 9 into the information display device cancompletely eliminate any distortions of the picture.

The information display device shown in FIG. 2 is different from thedevice of FIG. 1 described above in that it is adapted for display ofcolor information. In consequence, three video signals, and not one,corresponding to red, green and blue colors are supplied from thereceiver-amplifier unit 1 to the signal-to-image converter 5. Each suchvideo signal passes through its own corrector 6₁, 6₂, 6₃, of luminancedistortions of the displayed image.

The image contour detector 7 (FIG. 3) operates as follows. In thedifferentiating unit comprising the delay unit 12 and differenceamplifier 13, the input video signal (curve 91 in FIG. 12a) isdifferentiated by finding the difference between the original videosignal and the video signal (curve 92 in FIG. 12b) delay unit 12 for aperiod of approximately 50-100 ns. The differentiated video signal(curve 93 in FIG. 12c) is further carried through the full-waverectifier 14 in order to find its absolute value (curve 94 in FIG. 12d).

The corrector 6 of luminance distortions of the displayed image, shownin FIG. 4, eliminates spurious brightness modulation of the image bymultiplying the video signal (curve 95 in FIG. 13e) by the signal (curve96 in FIG. 13d) which is the function of the instantaneous scanningspeed. The signal proportional to the actual scanning speed (curve 96 inFIG. 13d) is produced by adding together the signals proportional to theaverage (for a period) scanning speed (curve 97 in FIG. 13c) and to theinterpulse average scanning speed (curve 98 in FIG. 13b) and subtractingtherefrom, for the period of displaying image contours, the average (fora period) scanning speed (curve 99 in FIG. 13a), that is the speed ofthe action retarding the scanning beam. The signal proportional to theinstantaneous scanning speed (curve 96 in FIG. 13d) is multiplied, inthe one-quadrant multiplier 16 (FIG. 4), by the original video signal(curve 95 in FIG. 13e) in order to correct the video signal (curve 100in FIG. 13f).

Referring to FIG. 5, a simpler embodiment of the corrector 6 ofluminance distortions of the displayed image has a circuit without theanalog multiplier. To reduce the brightness of image contours when thebeam is arrested, pulses (curve 102 in FIG. 14a) fed from the thresholdunit 8 are added to the original video signal (curve 101 in FIG. 14c).Also, in order to somewhat increase the brightness of the inter-contourbackground which is scanned at a somewhat higher speed, the originalvideo signal is mixed with the signal (curve 103 in FIG. 14b) of theinterpulse average component, which is taken from the output of thegeometrical distortion corrector 9 and, consequently, the video signalis corrected (curve 104 in FIG. 14d). The optimal balance between thevideo signal (curve 101 in FIG. 14c) and contour brightness suppressingpulses (curve 102 in FIG. 14a) can be achieved by proper selection ofresistors 29 (FIG. 5) and 32 in the circuit of the luminance distortioncorrector 6. The optimal balance between the video signal (curve 101 inFIG. 14c) and interpulse average components (curve 103 in FIG. 14b) canbe achieved by proper selection of resistors 30 (FIG. 5), 33 and 31 inthe circuit of the corrector 6.

The corrector 9 of geometrical distortions of the displayed image, whosefunctional block diagram is shown in FIG. 6, operates as follows.

Since the magnitude of the pulse-to-pulse average component should beinversely proportional to the duration of the interval between adjacentbeam arresting pulses, the corrector 9 should in some way realize thehyperbolic relationship between the magnitude of the interpulse averageand the duration of a respective time interval. Besides, the magnitudeof the interpulse average component should be known at the verybeginning of this interpulse time interval, when its duration is not yetapparent. It is for this reason, that the geometrical distortioncorrector 9 should inevitably comprise a buffer storage and thesought-for information is to be produced at the output of the corrector9 with a specific constant delay, e.g. for the horizontal scan periodT₁.

The circuit of the geometrical distortion corrector 9 comprises thesawtooth generator 38, logarithmic amplifier 39, and differentiatingunit 40, which together realize the hyperbolic relationship inaccordance with known mathematical formulas. The buffer storage in thiscase is the digital storage unit 44. Pulses are fed to the input of thegeometrical distortion corrector 9 from the output of the threshold unit8 (curve 105 in FIG. 15a), together with line sync pulses from the linesync output of the receiver-amplifier unit 1 (curve 106 in FIG. 15b).These pulses are united (curve 107 in FIG. 15c) in the OR circuit 34.Then they are sent through the delay unit 35 where they are delayed fora period approximately equal to the duration of the pulses, that isτ_(d) =τ_(p) (curve 108 in FIG. 15d). Next, these pulses are convertedin the sawtooth generator 38 into triangular pulses (curve 109 in FIG.15e) whose swing is proportional to the pulse separation (the length ofthe interpulse interval). Then the pulses are converted in thelogarithmical amplifier 39 into pulses (curve 110 in FIG. 15f) whoseswing is proportional to the logarithm of interpulse intervals. Furtheron, in the differentiating unit 40, the pulses are converted intosignals (curve 111 in FIG. 15g) whose magnitude at the end of eachpulse-to-pulse interval is inversely proportional to its duration. Thisvalue is separated and stored in the analog storage device 37 (curve 112in FIG. 15h) whose first input accepts, as control signals, undelayedpulses (curve 107 in FIG. 15c) fed from the output of the OR circuit 34.This analog quantity is further converted, in the analog-to-digitalconverter 43, into a digital code and stored in the digital storage unit44. After a time interval, which is somewhat less than the horizontalscanning period T₁, information is retrieved from the digital storage 44(curve 113 in FIG. 15i) at the desired instant. In this manner,information on the magnitude of the average interpulse component in thegeometrical distortion corrector 9 is retrieved with a delay equal tothe horizontal scanning period T₁.

In order to compensate for this delay, additional delay units rated fora period equal to the horizontal scanning period T₁ may be connected tofirst and second inputs of the corrector 6 and to the first input of thecontrol signal generator 10. The functional block diagram of thegeometrical distortion corrector 9, shown in FIG. 6, is a simplifiedcircuit illustrating only general principles of its operation. Thus, forexample, this block diagram omits, for simplicity, control circuitsresponsible for data addressing in the digital storage unit 44, bothduring the recording and readout processes.

The corrector 9 of geometrical distortions of the displayed image, whosefunctional block diagram is shown in FIG. 7, differs from the previousembodiment in that, first, the average interperiod component of thescanning speed is located between the leading, and not trailing, edgesof the contours, second, the previously sought-for hyperbolicrelationship between the average interpulse component and the durationof a respective time interval is replaced by its exponentialapproximation, and, third, an analog shift register is used as a bufferstorage.

Pulses fed from the treshold unit 8 (curve 114 in FIG. 16a) and delayedin the delay unit 46 for a period approximately equal to the pulseduration, that is τ_(d) =τ_(p) (curve 115 in FIG. 16b), rapily chargethe capacitor (not shown) of the peak detector 48 to a voltage equal tothe sweep of these pulses (curve 116 in FIG. 16e). The capacitor of thepeak detector 48 is then discharged exponentially with a specific presettime constant which is less than the horizontal scanning period T₁.

The output voltage of the peak detector 48 changes exponentially (curve116 in FIG. 16e). After the forward stroke of the horizontal scanning isover, the capacitor of the peak detector 48 discharges in a horizontalsync pulse (curve 117 in FIG. 16c) delayed in the delay unit 47 (curve118 in FIG. 16d) for the period τ_(d) =τ_(p). Undelayed horizontal syncpulses (curve 117 in FIG. 16c) and pulses produced by the threshold unit8 (curve 114 in FIG. 16a) are united into a sequence in the OR circuit52 (curve 119 in FIG. 16f), which is used to sample the exponentialvoltage (curve 116 in FIG. 16e) produced by the peak detector 48 at theend of the interpulse interval (curve 120 in FIG. 16g) in the firstanalog storage unit 51, of the analog shift register 50. The samesequence of pulses delayed in the delay unit 53 (FIG. 7) of the analogshift register 50 for a period τ_(d) =τ_(p) (curve 121 in FIG. 16h) isused to transfer the stored analog quantity from the first to the secondstorage unit 51 of the analog shift register 50 (curve 122 in FIG. 16i).

When a next pulse from the above sequence arrives at the output of theOR circuit 52, the first analog storage unit 51 of the analog shiftregister 50 stores a next average interpulse component at the output ofthe peak detector 48 (curve 120 in FIG. 16g), while the precedingquantity is shifted to the third analog storage unit 51 of the analogshift register 50 (curve 123 in FIG. 16j).

When a next pulse from the output of the OR circuit 52 arrives, thefirst analog storage unit 51 stores a new analog quantity of the averageinterpulse component, while other uneven analog storage units 51 shiftthe analog quantities from the preceding even analog storage unit 51.When these pulses (curve 119 in FIG. 16f) are over, the delayed pulses(curve 121 in FIG. 16h) shift all quantities from the uneven analogstorage units 51 to subsequent even analog storage units 51 of theanalog shift register 50.

Since N outputs of all uneven analog storage units 51 are connected to Ninputs of the multiplexer 56, any analog value of the average interpulsecomponent can be transferred to the output in response to controlvoltages (curves 124, 125, 126 in FIGS. 16p, 16r, 16s) fed fromrespective stages of the reversible counter 54 where the address of theanalog storage unit 51 of the analog shift register 50 is produced. Thisaddress indicates where the value of the analog quantity of the averageinterpulse component of the scanning speed (curve 127 in FIG. 16u)should be taken off.

The control signal generator 10 whose electrical circuit is shown inFIG. 8 operates as follows.

The signal of average interpulse components of the scanning speed (curve128 in FIG. 17a) is inverted in the analog inverter 57 and supplied tothe input of the integrator 58. Also applied to this input of theintegrator 58 are pulses from the output of the corrector 9 (curve 129in FIG. 17b). The result of integration is a triangular voltage of thedesired magnitude and polarity (curve 130 in FIG. 17c), which is outputamplifier 11 into triangular current.

In the control signal generator 10 whose electrical circuit is shown inFIG. 9, both input signals (curves 128 and 129 in FIGS. 17a and 17b) aresupplied to the input of the difference amplifier 70 whose output signalis fed to the integrator 71 producing the same triangular voltage (curve130 in FIG. 17c).

The device for display of information, disclosed herein, achieves acomplete arrest of the scanning beam for the period when image contours(or edges) are displayed. In this manner, any effect of the insufficientresolution of data generation and storage units on the size of theresulting unsharpness zone is eliminated. In consequence, the sharpnessof the displayed images is almost doubled. In addition, any distortionsof image brightness and geometrical shape, which may be caused byvariations in the horizontal scanning speed, are practically eliminatedtoo.

This invention can be used for reproduction of information astwo-gradation (in computer displays, radar indicators) or half-tone (asin television receivers, or closed-circuit television monitors)black-and-white or color pictures.

We claim:
 1. A device for displaying information, comprising: a receiverunit having a line sync output, a frame sync output, at least oneinformation output, and an input connected to a source of an informationsignal, and to receive, amplify and separate an information videosignal, as well as line and frame synchronizing signals; horizontal andvertical scanning generators to produce a standard pattern and havingtheir inputs connected, respectively, to the line and frame sync outputsof the receiver-amplifier unit; an information video signal-to-imageconverter, which is to produce an image and has a first input connectedto an output of the horizontal scanning generator, a second inputconnected to an output of the vertical scanning generator, and a thirdinput electrically connected with the information output of thereceiver-amplifier unit; an output amplifier having an output connectedto a fourth input of the signal-to-image converter; a detector ofcontours of the displayed image, which is to produce a signal to controlhorizontal scanning during display of the image contours and has aninput connected to the information output of the receiver-amplifierunit; a threshold unit connected to an output of the image contourdetector and to obtain, when displaying image contours, an insignificanthorizontal scanning speed, a control signal generator which producessawtooth voltage when displaying image contours and has an inputconnected to the output of the threshold unit and an output connected tothe input of the output amplifier to convert the sawtooth voltage intosawtooth current producing a deflection field having the same strengthas the field produced by the horizontal scanning generator but ofopposite polarity.
 2. A device as claimed in claim 1, further comprisinga displayed image geometric distortion corrector to prevent spacialshifts of the image contours which has a first input connected to theoutput of the threshold unit, and a second input connected to the linesync output of the receiver-amplifier unit, and an output connected to asecond input of the control signal generator.
 3. A device as claimed inclaim 2, further comprising a corrector of luminance distortions of thedisplayed image, to prevent distortions of brightness levels of thecontours and background and being inserted between the informationoutput of the receiver-amplifier unit and the third input of thesignal-to-image converter, a second input of said luminance distortioncorrector being connected to the output of the threshold unit, while athird input is connected to the output of the geometrical distortioncorrector.
 4. A device as claimed in claim 3, further comprising twoadditional correctors of luminance distortions of the displayed image,which are to correct intensity levels of chrominance signals and havefirst inputs connected respectively to the second and third informationoutputs of the receiver-amplifier unit, second inputs connected to theoutput of the threshold unit, third inputs connected to the output ofthe geometrical distortion corrector, and outputs respectively connectedto the fifth and sixth inputs of the signal-to-image converter.
 5. Adevice as claimed in claims 3 or 4, wherein the luminance distortioncorrector comprises a difference amplifier to subtract the signalproduced by the threshold unit from the original information signalsummed up with the signal produced by the geometrical distortioncorrector, said difference amplifier having a first input connected tothe output of the threshold unit, a second input connected to the outputof the geometrical distortion corrector, a third input connected to aninformation output of the receiver-amplifier unit, and an outputconnected to a third input of the signal-to-image converter.
 6. A deviceas claimed in claim 2, wherein the corrector of geometrical imagedistortions comprises delay units, an analog storage unit, an OR circuithaving a first input connected to the output of the threshold unit andto the first input of analog storage unit, a second input connected tothe line sync output of the receiver-amplifier unit and to the secondinput of the unit, and an output connected to inputs of the respectivedelay units, a logarithmic amplifier, a differentiating network, asawtooth voltage generator having an input connected to the output ofthe delay unit and an output connected to the logarithmical amplifiercoupled with the differentiating network having an output connected to asecond input of the analog storage unit, an analog-to-digital converter,a digital-to-analog converter, a digital storage unit having a firstinput connected to the delay unit, a second input connected to theoutput of the analog-to-digital converter coupled with the output of theanalog storage unit, while an output of the digital storage unit isconnected to the digital-to-analog converter an output of which is theoutput of the geometrical image distortion corrector, and is connectedto the input of the control signal generator.
 7. A device as claimed inclaim 2, wherein the corrector of geometrical image distortionscomprises a peak detector, an electronic switch, an analog shiftregister, a first delay unit having an input connected to the output ofthe threshold unit and an output connected to the peak detector, asecond delay unit having an input connected to the line sync output ofthe receiver-amplifier unit and an output connected to a control inputof the electronic switch having one signal output connected to a commonbus, while the other output thereof is connected to a second input ofthe peak detector having an output connected to a signal input of theanalog shift register, an OR circuit having one input connected to theoutput of the threshold unit, the other input connected to the line syncoutput of the receiver-amplifier unit, and an output connected to thecontrol input of the analog shift register, a reversible counter, adelay unit having an input connected to the output of the OR circuit andan output connected to the subtracting input of the reversible counterhaving a summing input connected to the output of the OR circuit, and amultiplexer having N signal inputs connected to N outputs of the analogshift register, M control inputs of which are connected to outputs ofthe reversible counter, M being greater than or equal to log N, while anoutput of the multiplexer is the output of the corrector of geometricalimage distortions, which is connected to the input of the control signalgenerator.
 8. A device as claimed in claim 7, wherein the analog shiftregister comprises 2N-1 series connected analog storage units, unevenstorage units have outputs connected to signal inputs of themultiplexer, and a delay unit has an input connected to control inputsof uneven analog storage units and an output connected to control inputsof the analog storage units.